FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -Port 21 is for the control channel, and port 20 is for the data channel. Learn how these two channels are used. You may already know that, when FTP commands cross the wire, they use TCP port 21 by default. You may also know that port 20 is assigned to the FTP data channel by default.

Detailed explanation-2: -Port 21/TCP 21/TCP is used for the control channel – the client and server talk over this port and when the client is ready to upload or download a file or directory, the client and server discuss what port number they want to use for the data channel for this single transfer.

Detailed explanation-3: -Anyway, port 21 is used for FTP protocol (and FTPS with explicit TLS/SSL encryption). Port 22 is used for SSH/SFTP protocol. WinSCP automatically uses the correct port number, when you specify the respective protocol. Usually it is not necessary to specify the port number explicitly.

Detailed explanation-4: -Ports 20 and 21: These Ports are used for FTP (file transfer protocol) connection. FTP uses two TCP connections for communication. Port 21 is used for pass control information. And the other port 20 is used to send the data files between the client and the server.

Detailed explanation-5: -Explanation. FTPS is FTP (File Transfer Protocol) over SSL/TLS, which traditionally uses TCP port 990, while SCP (Secure Copy Protocol) is implemented on top of SSH (Secure Shell), which traditionally uses TCP port 22. FTP uses port 21, SFTP uses port 22, FTPS uses port 990.